Knowing an accurate location of mobile station (MS) can benefit network operators in many ways. For example, a continuously mobile MS may indicate that a subscriber is driving, and thus a location of the subscriber can be narrowed down to a nearby road if combined with a map. By way of another example, knowledge of a location of an MS may be used to determine the kind of value-added services to provide to the MS, such as which local advertisements to push to the MS. Recent years have seen a tremendous growth of interest in location-based services. Knowing the location of subscribers can help carriers team up with local businesses to provide instant mobile business information. In addition, statistics of subscribers' location information can help network operators better understand their network traffic distribution and thus allow the operators to better design and deploy their base stations, identify coverage holes, and minimize traffic loss.
Although an MS equipped with a Global Positioning Satellite (GPS) system can provide very accurate location information, there are many limitations preventing network operators from benefiting from GPS enabled devices. First, it may take years for every mobile device to include a GPS device, especially for emerging markets. Second, GPS information is not available in an indoor environment. And third, operators may not be able to obtain GPS information from subscribers due to privacy issues. Other location methods, such as correlating received signal strength and distance from a receiver, are far from accurate. As a result, use of location-based methods for mobility determination is not a good choice for operators at this time.
Therefore, a need exists for an improved method and apparatus for more accurately determining a real-time location of an MS without changing the components of existing infrastructure or depending on enhanced MS capabilities.
One of ordinary skill in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention. Also, common and well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.